For three quarters, they were a shell of themselves. Mere mortals on the field, and nothing more.

These New England Patriots didn’t elicit fear in their opponents, nor did they resemble the perennial power they’ve come to be. The Jets could sense it. And they preyed upon that vulnerability.

The fabled Patriots mystique had disintegrated long before Tom Brady and the defending Super Bowl champions stepped onto the field at MetLife Stadium. The Brady-Bill Belichick tandem looked easily beatable, and the Patriots were quickly bullied into a double-digit deficit.

In the end, though, too many missed opportunities by the Jets and one costly and controversial fumble call paved the way for New England to escape with a 24-17 victory in enemy territory. But Sunday’s outcome — awful officiating aside — is proof that the Patriots have their own set of problems. And the rest of the AFC East, particularly the Bills, should take note.

Brady ended the game with more regular-season wins (187) than any quarterback in league history. But he started the game with a 69.2 QB rating on 12 of 25 passing for 145 yards, one touchdown and an interception. He didn’t look particularly good and neither did his defense, which has struggled to put together a strong four-quarter effort this season.

The Patriots are the first team in NFL history to allow six straight individual 300-yard passing games. Jets’ journeyman Josh McCown — who, at 38, has a standing offer to be a Browns assistant coach whenever he retires — was the latest quarterback to do so, totaling 354 in a losing effort.

But while they may have felt cheated, they certainly were not defeated. If anything, they were encouraged.

“They own this division,” Jets receiver Jeremy Kerley said of the Patriots, “but every time they play us, they know they better come with it. Cause if they don’t, they’re going to get their butt whupped. It all comes down to just making more plays. They made a couple more plays than we did.”

The Jets — a rebuilt work in progress, just like Sean McDermott’s revamped Bills team — jumped all over Brady and the Patriots after the opening kick and stayed close down the stretch. But here is where Todd’s team faltered.

“If you get a team behind,” Patriots safety Devin McCourty said matter-of-factly, “you’ve got to put your foot on their throat and finish them off.”

And therein lies the lesson for the Bills and every AFC team that faces the Patriots: Never take your foot off their throat.

That’s what good teams do.

Brady is a beast. We know that. But the Patriots defense, at least for now, is its Achilles heel.

The unit knows that opponents will look to exploit it, that opposing quarterbacks will be gunning for its secondary. And, not surprisingly, the Patriots welcome the challenge.

“I love it. I love it,” safety Duron Harmon said. “It’s like somebody coming for what’s yours. They might have that chip on their shoulder, but we’ve got that chip, too. To let people know, you can’t have what’s ours.”

Jets players acknowledged the overturned Austin Seferian-Jenkins touchdown was a “huge” play that had massive ramifications on the final score. “You take that away, it’s a totally different game,” Kerley said.

But the fumble call shouldn’t overshadow New England’s glaring issues.

The Patriots have the top-ranked offense (412.0 yards per game) and the No. 1 passing attack (309.8), yet their defense is dead last in total yards (440.7 yards per game) and passing yards allowed (324.8).

They had “trouble finishing the Jets as always,” Belichick noted, adding: “A lot of our wounds were self-inflicted. … It felt like we were kind of our biggest enemy the first thing of the game.”

It’s not too often that we hear the disciplined Patriots discussing their own mental mistakes or mechanics. But good teams find a way to grind out victories. It won’t always be pretty. In fact, some days those wins will be ugly.

But the best teams find a way to stack wins regardless.

“Hopefully, we’ll look back and say, this Jets game helped us in Week 13 or 14 when we had to gut out an ugly win on the road,” Harmon said. “This is the NFL. Every team has talented players. But it really comes down to a couple possessions.”